Re: [PATCH] drm/mst: Fix up u64 division

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Sean Paul <sean@poorly.run>
Cc: David Airlie <airlied@linux.ie>,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	dri-devel@lists.freedesktop.org,
	Sean Paul <seanpaul@chromium.org>,
	Harry Wentland <hwentlan@amd.com>,
	Juston Li <juston.li@intel.com>
Subject: Re: [PATCH] drm/mst: Fix up u64 division
Date: Wed, 6 Nov 2019 20:28:13 +0200	[thread overview]
Message-ID: <20191106182813.GV1208@intel.com> (raw)
In-Reply-To: <20191106173622.15573-1-sean@poorly.run>

On Wed, Nov 06, 2019 at 12:36:15PM -0500, Sean Paul wrote:
> From: Sean Paul <seanpaul@chromium.org>
> 
> Use do_div to divide rem_nsec instead of /.
> 
> Fixes: 12a280c72868 ("drm/dp_mst: Add topology ref history tracking for debugging")
> Cc: Juston Li <juston.li@intel.com>
> Cc: Imre Deak <imre.deak@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Harry Wentland <hwentlan@amd.com>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Sean Paul <sean@poorly.run>
> Cc: Lyude Paul <lyude@redhat.com>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Maxime Ripard <mripard@kernel.org>
> Cc: David Airlie <airlied@linux.ie>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: dri-devel@lists.freedesktop.org
> Signed-off-by: Sean Paul <seanpaul@chromium.org>
> ---
>  drivers/gpu/drm/drm_dp_mst_topology.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
> index 11adc4b6ccfe..d2da5f113f16 100644
> --- a/drivers/gpu/drm/drm_dp_mst_topology.c
> +++ b/drivers/gpu/drm/drm_dp_mst_topology.c
> @@ -1512,10 +1512,10 @@ __dump_topology_ref_history(struct drm_dp_mst_topology_ref_history *history,
>  		nr_entries = stack_depot_fetch(entry->backtrace, &entries);
>  		stack_trace_snprint(buf, PAGE_SIZE, entries, nr_entries, 4);
>  
> -		drm_printf(&p, "  %d %ss (last at %5llu.%06llu):\n%s",
> +		drm_printf(&p, "  %d %ss (last at %5llu.%06u):\n%s",
>  			   entry->count,
>  			   topology_ref_type_to_str(entry->type),
> -			   ts_nsec, rem_nsec / 1000, buf);
> +			   ts_nsec, do_div(rem_nsec, 1000), buf);

Or just change rem_nsec to u32 since that's what do_div() gives you.

>  	}
>  
>  	/* Now free the history, since this is the only time we expose it */
> -- 
> Sean Paul, Software Engineer, Google / Chromium OS

-- 
Ville Syrjälä
Intel
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